1. Field of the invention
The invention relates to a method for producing a buidling element by forming a mixture of fly ash, slaked lime, water and a coarse particles comprising material into an unhardened building element and by hardening said unhardened building element at elevated temperature and in a water vapor containing atmosphere.
2. Review of prior art
Such a method is known from the published German patent application DE-A-No. 3 321 899.
In said application a method is described in which crushed bottomslag of a coal fired powerstation, fly ash, slaked line and water are mixed; the mixture is formed into brick-form elements after which the bricks are hardened with use of steampressure at elevated temperature. Hardening preferably is carried out at a pressure of 14-16 bar and a temperature of 180.degree.-220.degree. C.
This known method has the disadvantage that for the hardening process a high temperature and high vapour pressure are necessary while the use of coarse particles comprising materials is restricted to crushed bottomslag.